Hydrocarbon reactivity in the superacid SbF5/HF: An ab initio molecular dynamics study

Simone Raugei, Michael L. Klein

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The free energy profiles for the protonation of simple alkanes in SbF5/HF superacid solution have been studied by ab initio molecular dynamics simulations. It is shown that the presence of extremely reactive protons at high SbF5 concentrations open reaction channels for the C-H protonation with a considerably decreased barrier with respect to dilute solutions and the gas phase. It is proposed that this, along with the progressive presence of neutral SbF5, is responsible for the experimentally observed increased reactivity of these solutions as the concentration of SbF5 is increased. It has also been found that in solution an electrostatic stabilization of the transition state contributes to the lowering of the reaction barrier. In the case of ethane C-H protonation is in competition with C-C protonation. In fact, nearby, the transition state of C-C protonation, alternative reaction pathways that lead to the C-H protonation are accessible.

Original languageEnglish
Pages (from-to)11596-11605
Number of pages10
JournalJournal of Physical Chemistry B
Volume106
Issue number44
DOIs
Publication statusPublished - Nov 7 2002

Fingerprint

Protonation
Hydrocarbons
Molecular dynamics
reactivity
hydrocarbons
molecular dynamics
ethane
alkanes
Alkanes
Ethane
stabilization
free energy
electrostatics
vapor phases
Paraffins
Free energy
protons
Protons
Electrostatics
Stabilization

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Hydrocarbon reactivity in the superacid SbF5/HF : An ab initio molecular dynamics study. / Raugei, Simone; Klein, Michael L.

In: Journal of Physical Chemistry B, Vol. 106, No. 44, 07.11.2002, p. 11596-11605.

Research output: Contribution to journalArticle

@article{2df598b9f0b3458e9aa60c3126f409ad,
title = "Hydrocarbon reactivity in the superacid SbF5/HF: An ab initio molecular dynamics study",
abstract = "The free energy profiles for the protonation of simple alkanes in SbF5/HF superacid solution have been studied by ab initio molecular dynamics simulations. It is shown that the presence of extremely reactive protons at high SbF5 concentrations open reaction channels for the C-H protonation with a considerably decreased barrier with respect to dilute solutions and the gas phase. It is proposed that this, along with the progressive presence of neutral SbF5, is responsible for the experimentally observed increased reactivity of these solutions as the concentration of SbF5 is increased. It has also been found that in solution an electrostatic stabilization of the transition state contributes to the lowering of the reaction barrier. In the case of ethane C-H protonation is in competition with C-C protonation. In fact, nearby, the transition state of C-C protonation, alternative reaction pathways that lead to the C-H protonation are accessible.",
author = "Simone Raugei and Klein, {Michael L.}",
year = "2002",
month = "11",
day = "7",
doi = "10.1021/jp026395l",
language = "English",
volume = "106",
pages = "11596--11605",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "44",

}

TY - JOUR

T1 - Hydrocarbon reactivity in the superacid SbF5/HF

T2 - An ab initio molecular dynamics study

AU - Raugei, Simone

AU - Klein, Michael L.

PY - 2002/11/7

Y1 - 2002/11/7

N2 - The free energy profiles for the protonation of simple alkanes in SbF5/HF superacid solution have been studied by ab initio molecular dynamics simulations. It is shown that the presence of extremely reactive protons at high SbF5 concentrations open reaction channels for the C-H protonation with a considerably decreased barrier with respect to dilute solutions and the gas phase. It is proposed that this, along with the progressive presence of neutral SbF5, is responsible for the experimentally observed increased reactivity of these solutions as the concentration of SbF5 is increased. It has also been found that in solution an electrostatic stabilization of the transition state contributes to the lowering of the reaction barrier. In the case of ethane C-H protonation is in competition with C-C protonation. In fact, nearby, the transition state of C-C protonation, alternative reaction pathways that lead to the C-H protonation are accessible.

AB - The free energy profiles for the protonation of simple alkanes in SbF5/HF superacid solution have been studied by ab initio molecular dynamics simulations. It is shown that the presence of extremely reactive protons at high SbF5 concentrations open reaction channels for the C-H protonation with a considerably decreased barrier with respect to dilute solutions and the gas phase. It is proposed that this, along with the progressive presence of neutral SbF5, is responsible for the experimentally observed increased reactivity of these solutions as the concentration of SbF5 is increased. It has also been found that in solution an electrostatic stabilization of the transition state contributes to the lowering of the reaction barrier. In the case of ethane C-H protonation is in competition with C-C protonation. In fact, nearby, the transition state of C-C protonation, alternative reaction pathways that lead to the C-H protonation are accessible.

UR - http://www.scopus.com/inward/record.url?scp=0037038560&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037038560&partnerID=8YFLogxK

U2 - 10.1021/jp026395l

DO - 10.1021/jp026395l

M3 - Article

AN - SCOPUS:0037038560

VL - 106

SP - 11596

EP - 11605

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 44

ER -